1. Field of the Invention
The present invention relates to technology for raising the quality of three-dimensional images (three-dimensional stereoscopic images), and also relates to technology that is applicable to a wide range of devices that handle three-dimensional images (three-dimensional video), such as a camera (imaging device) that performs three-dimensional imaging, a display device that displays three-dimensional images (three-dimensional video), and an image processing device that processes three-dimensional images (three-dimensional video).
2. Description of the Related Art
There are known to be three-dimensional imaging devices that capture three-dimensional images (left eye images and right eye images) in a state in which binocular disparity exists in order to reproduce three-dimensional images by displaying three-dimensional images (left eye images and right eye images) with a display device that can project images to the left and right eyes independently (hereinafter, referred to as a “three-dimensional display device”).
In three-dimensional imaging, three-dimensional images (left eye images and right eye images) acquired in a state in which the far scene (subject in the far scene) and the near scene (subject in the near scene) have a high degree of disparity are images for which three-dimensional viewing is difficult since the fusion limit in human three-dimensional vision is exceeded, or are images that cause the person viewing them to feel fatigued (fatiguing images). In order to avoid the generation of such poor three-dimensional images, there is technology for obtaining favorable three-dimensional images by performing disparity adjustment and stereo base adjustment (hereinafter, referred to as “SB adjustment”), and such technology is widely used in professional three-dimensional imaging for movies and the like.
Regarding disparity adjustment, with technology used mainly in the case where the far scene (subject in the far scene) exceeds the fusion limit, performing disparity adjustment in order to non-linearly compress the distance to the far scene (subject in the far scene) enables bringing the far scene (subject in the far scene) that was not easily viewable in three-dimensional viewing closer so as to acquire three-dimensional images that are easily viewable in three-dimensional viewing (easily three-dimensionally viewable three-dimensional images).
Also, stereo base adjustment enables reducing the dynamic range of disparity by reducing the gap between two cameras (a camera for capturing left eye images and a camera for capturing right eye images) (by reducing the stereo base (interaxial distance)). For this reason, performing three-dimensional imaging after performing stereo base adjustment as described above enables acquiring three-dimensional images in which the entirety of the image from the near scene (subject in the near scene) to the far scene (subject in the far scene) falls within the fusion area.
Also, in the case of displaying three-dimensional images with a small-sized display device as well, the far scene is compressed since the disparity of the three-dimensional images (left eye images and right eye images) is reduced. Accordingly, in this case, the three-dimensional images displayed with the small-sized display device are easily viewable three-dimensional images.
In three-dimensional imaging, taking advantage of the above-described imaging technology (disparity adjustment and stereo base adjustment) enables capturing three-dimensional images that are sufficiently easily viewable images (easily three-dimensionally viewable three-dimensional images) when three-dimensionally displayed in a predetermined display environment (e.g., see Japanese Patent No. 3157384).
However, with the above-described conventional technology, easily viewable three-dimensional images (easily three-dimensionally viewable three-dimensional images) are acquired by reducing desirable disparity (by reducing the disparity from the original value such that subjects serving as targets in three-dimensional imaging fall within the fusion area of three-dimensional vision) in consideration of the fusion limit of three-dimensional vision, and therefore such conventional technology is not desirable from the viewpoint of naturalness in three-dimensional appearance and sense of perspective in three-dimensional images. Accordingly, three-dimensional images acquired using the above-described conventional technology (technology using disparity adjustment and stereo base adjustment) have a problem related to three-dimensional image quality.
With technology using disparity adjustment, easily viewable (easily three-dimensionally viewable) three-dimensional images can be obtained, but since the distance to the far scene (distance from the position of the imaging device to the subject in the far scene) is non-linearly compressed, three-dimensional images that have been subjected to disparity adjustment are accompanied by a phenomenon in which the depth becomes flat (cardboard cutout effect).
Also, with technology using SB adjustment, the overall sense of perspective in acquired three-dimensional images is reduced (the distance from the nearest point (the position of the subject formed at the closest position in three-dimensional video display) to the most distant point (the position of the subject formed at the farthest position in three-dimensional video display) is reduced), thus producing a phenomenon in which the three-dimensional appearance of individual subjects is reduced.
Accordingly, when using the above-described conventional technology, in both cases the acquired three-dimensional images tend to be low-quality images that are poor in terms of three-dimensional appearance and sense of perspective.
In light of the above-described problems, an object of the present invention is to achieve a three-dimensional image processing device, a three-dimensional image processing method, and a program that obtain high-quality three-dimensional images by giving a natural three-dimensional appearance to images that were captured with little disparity and have a poor three-dimensional appearance.